Rational Design of Cobalt‐Based Prussian Blue Analogues via 3d Transition Metals Incorporation for Superior Na‐Ion Storage

Understanding the relationship between structure regulation and electrochemical performance is key to developing efficient and sustainable sodium‐ion batteries (SIBs) materials. Herein, seven Cobalt‐M‐based (M=V, Mn, Fe, Co, Ni, Cu, Zn) Prussian blue analogues (CoM‐PBAs) are designed as anodes for SIBs via a universal low‐energy co‐precipitation approach with the strategic inclusion of 3d transition metals. Density Functional Theory (DFT) simulation and experimental validation reveal that a moderate p‐band center of cyanide linkages (‐CN‐) is more favorable for Na+ intercalation and diffusion, while the d‐band center of metal cations is linearly related to electrode stability. Among seven CoM‐based PBAs, CoV‐PBAs possess the best sodium‐ion adsorption/diffusion kinetics and overall cycling performance, including high specific capacity (565 mAh/g at 0.1 A/g), cycling stability (over 15000 cycles with 97.7% capacity retention), and superior rate capability (174.7 mAh/g at 30 A/g). In‐situ/ex‐situ techniques further demonstrate that the π‐electron regulation by V introduction enhances the reversibility and kinetics of redox reactions. Moreover, the study identified the "p‐band center" and "d‐band center" may serve as key descriptors for quantifying the capability and stability of other‐type bimetal Co‐based anodes (oxides, phosphides, sulfides, and selenides) with similar theoretical capacity, offering a potentially transformative approach for selecting practical SIB electrode materials.